Method for making stator of rotary electric machine

ABSTRACT

A rotary electric machine has a stator core and a winding. The winding has a plurality or sub-winding sets which are mounted on the stator in the order. Each of the sub-winding sets has a plurality of phase windings. Each of the phase windings is made of a continuous wire. The sub-winding sets are formed into a cylindrical shape having a plurality of straight portions and turn portions before the sub-winding sets are mounted on the stator core. The turn portions are regularly arranged to avoid collisions between the turn portions. It is possible to avoid collisions since the winding is mounted on.

This is a Divisional of application Ser. No. 09/842,915 filed Apr. 27,2001 now U.S. Pat No. 6,703,750. The entire disclosure of the priorapplication is hereby incorporated by reference herein in its entirety.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Applications No.2000-127226 filed on Apr. 27, 2000 and No. 2000-153140 filed on May 24,2000 the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a stator of a rotary electric machine.

2. Description of Related Art

JP-A-11-299153 discloses an alternator for a vehicle which has a statorwith curled coil ends. The portions of the coil, disposed between slotswhich are spaced apart by a predetermined pitch, are curled and twistedin a radial direction at the center. Therefore, all curled portions ofthe coil are circumferentially arranged side by side. In thisarrangement, it is difficult to arrange the curled portions to avoidcollisions with other portions, since the coil is widened at the curledportions especially when a thick coil wire is used.

JP-B-2927288 and JP-A-11-164506 disclose alternators for a vehiclehaving stator windings which are made of a plurality of segments weldedto each other. In this arrangement, the welded portions require acomplicated manufacturing process and an additional insulating process.

SUMMARY OF THE INVENTION

The present invention addresses these drawbacks by providing an improvedstator arrangement and an improved manufacturing method.

It is therefore an object of this invention to provide an improvedstator of a rotary electric machine.

It is a further object of this invention to provide a stator of a rotaryelectric machine which has a novel arrangement of windings.

According to a first aspect of the present invention, the stator of therotary electric machine comprises a plurality of sub-winding sets. Eachsub-winding set comprises a plurality of phase windings. Each of thephase windings is made of a continuous wire providing an individual coilon a stator core. The phase windings in the same phase are connected viaconnecting portions provided outside of the stator core. The turnportions are arranged on each of the sub-winding sets. Therefore, it ispossible to avoid collisions between the turn portions. The continuouswire is capable of reducing connections on the poly-phase winding.

In the present invention, the phase winding may have at least threestraight portions and two turn portions which are provided by thecontinuous wire.

The sub-winding sets can be mounted on the stator core by shrinking thesub-winding sets, inserting the shrunken sub-winding sets into a cavityof the stator core and expanding the shrunken sub-winding sets.

According to the another aspect of the present invention, a stator of arotary electric machine comprises a poly-phase winding comprising aplurality of phase windings. Each of the phase windings is made of acontinuous wire. The turn portions of each windings are arranged side byside with respect to a radial direction on one side of the stator core.It is possible to avoid collisions between the turn portions since theturn portions are arranged side by side. The continuous wire reduces thenumber of connections on the poly-phase winding.

The poly-phase winding may be formed by preparing a poly-phase wavewinding having first turn portions, and forming at least two straightportions and a second turn portion between them on each of the middleportions of the poly-phase wave winding. The second turn portions may beformed by folding the wave winding at a predetermined position andshifting the straight portions placed on both sides of the predeterminedposition by a predetermined magnetic pole pitch. The straight portionsmay be shifted before folding.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will beappreciated, as well as methods of operation and the function of therelated parts, from a study of the following detailed description, theappended claims, and the drawings, all of which form a part of thisapplication. In the drawings:

FIG. 1 is a sectional view of an alternator for vehicle according to afirst embodiment of the present invention;

FIG. 2 is a perspective view of a winding according to the firstembodiment of the present invention;

FIG. 3 is a diagram of the winding according to the first embodiment ofthe present invention;

FIG. 4 is a plan view of the coil end according to the first embodimentof the present invention;

FIG. 5 is a sectional view of the stator according to the firstembodiment of the present invention;

FIG. 6 is a plan view of the coil end viewing from radial outsideaccording to the first embodiment of the present invention;

FIG. 7 is a plan view of the coil end according to a second embodimentof the present invention;

FIG. 8 is a sectional view of an alternator for vehicle according to athird embodiment of the present invention;

FIG. 9 is a perspective view of a winding according to the thirdembodiment of the present invention;

FIG. 10 is a diagram of the winding according to the third embodiment ofthe present invention;

FIG. 11 is a diagram of the winding according to the third embodiment ofthe present invention;

FIG. 12 is a diagram of the winding according to the third embodiment ofthe present invention; and

FIG. 13 is a sectional view of the stator according to a fourthembodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

An alternator for a vehicle according to a first embodiment of thepresent invention is described with reference to the drawings. FIGS. 1through 6 show the first embodiment of the present invention. FIG. 1shows a general structure of the alternator. FIG. 2 and FIG. 3 show anindividual X-phase winding. FIG. 4 shows two X-phase windings. FIG. 5shows an arrangement of wires in a slot. FIG. 6 shows a part of anassembled stator viewing from a radial outside.

The alternator 1 has a shaft rotatably supported on a frame 4. A pulley20 driven by an engine is fixed on a front end of the shaft. A rotor 2and slip rings 9 and 10 are fixed on the shaft 21. The rotor 2 has apair of pole cores 71 and 72 and a field winding 8 connected to the sliprings 9 and 10. Each of the pole cores 71 and 72 provides eight magneticpoles arranged circumferentially. The magnetic poles define a magneticpole pitch. Cooling fans 11 and 12 are disposed on both sides of therotor 2.

A stator 3 is supported on the frame 4 having a cylindrical stator core32 and a stator winding 31. The stator core 32 is located opposite tothe magnetic poles of the rotor 2. The stator core 32 has slots 35 whichopen on axial ends and radially inside the stator core 32. As shown inFIG. 5, an insulator 34 insulates an inside surface from accommodatedwindings 31. Each of the slots 35 provides four positions in radiallyarranged layers to accommodate portions of wires.

The stator winding 31 has portions accommodated in the slots 35 and afirst and second coil end groups 312 a. The wires are aligned in aradial direction in the slots 35.

The frame 4 has a pair of axial inlet openings 41 located on front andrear side walls and a pair of radial outlet openings 42 located radiallyoutside of the first and second coil end groups 312 a and 312 b. Theframe 4 may further support a control member having a three-phaserectifier and an output terminal 6.

In operation, an engine rotates the pulley 20, field current is suppliedto the field winding 8 through the slip rings 9 and 10. The rotor 2rotates and generates a rotating magnetic field to induce an AC currentin the stator winding 31. The induced current in the stator winding 31is rectified and supplied as DC power through the output terminal 6. Thecooling fan 11 generates cooling wind flowing through the second coilend group 312 a. The cooling fan 12 generates cooling wind flowingthrough the first coil end group 312 a.

The stator winding 31 has two sub-winding sets 31 a and 31 b. Each ofthe sub-winding sets, has three individual phase windings, X, Y andZ-phase windings. Therefore, the stator 31 has two individual windingshaving the same electric phase. For instance, a phase winding Xa in afirst sub-winding set and a phase winding Xb in a second sub-winding setare connected to provide a X-phase winding of the poly-phase winding.The phase windings may be connected in either series or parallel. Theconnections are provided outside of the stator core after all of thephase windings are mounted on the stator core 32.

As shown in FIG. 2 and FIG. 3, the phase winding is made of a continuousjointless wire. The continuous wire provides at least one individualcoil on the stator core 32. For instance, the continuous wire has atleast three straight portions 311 a. In this embodiment, the continuouswire provides an individual coil fully around the stator core 32.

The phase winding Xa in the first winding set has a start end 3120, afinish end 3121, a plurality of straight portions 311 a and a pluralityof turn portions 312 c. The turn portions 312 c form the coil end groups312 a on opposite sides. The straight portions 311 a occupy outer layers31 a 1 and inner layers 31 a 2. The outer layers 31 a 1 and inner layers31 a 2 are stacked in a radial direction in the slots 35.

Each turn portion 312 c connects a pair of straight portions 311 a whichare disposed in different slots 35, spaced apart by the magnetic polepitch and disposed in the adjacent layer positions in theircorresponding slots. For instance, each turn portion 312 c connects anouter layer 31 a 1 and an inner layer 31 a 2 in different slots.Therefore, the straight portions 311 a which are radially adjacent inthe same slot are connected to each different turn portions extending inopposite directions.

The turn portion 312 c has a center portion 311 twisted in a radialdirection to provide a radial step and a pair of half portions 313 and314 shifted a predetermined radial distance connected to opposite sideof the center portion. The center portions 311 are also bent so that thepair of half portions 313 and 314 are inclined. The center portions 311are placed on teeth formed between the slots 35 since the half portionshave the same length.

The straight portions 311 a and the turn portions 312 c are alternatelyconnected to form a wave winding from the start end 3120 to athirty-fourth slot in ascending order. An irregular turn portion 312 dis used between the thirty-fourth and first slots to provide a reverseconnection. Then, a reverse wave winding is formed from the first slotto the finish end 3121 through a fourth slot in descending order.Therefore, the phase winding is wound around the stator core two times.The irregular turn portion 312 d is not twisted to connect the straightportions 311 a in the same layer.

The phase windings Ya and Za of the first sub-winding set are alsoformed in a similar manner for different slots. Each of the phasewindings may be composed of a wave winding which is wound around thestator core once.

In a manufacturing process, each of the phase windings are individuallyformed and arranged into a cylindrical arrangement as the firstsub-winding set. The phase windings can be assembled by loosening eachphase windings and by separating the wave windings. The cylindricalfirst sub-winding set is shrunken to reduce a diameter by compressingfrom outside, and inserted into a center cavity of the stator core 32.Then, the shrunken sub-winding set is expanded to insert the straightportions 311 a into the slots 35. It is preferable to use a spring backforce to expand the shrunken sub-winding set.

Further, the second sub-winding set is formed and inserted in a similarmanner. After that, ends 322 protruded from the teeth formed between theslots 35 are plastically deformed for narrowing the width of the inneropenings of the slots 35. The sub-winding set may be manufactured by amethod described in the following embodiment.

The phase windings in the same electric phase are connected in series toprovide a single phase winding in the poly-phase winding 31. Forinstance, the phase winding Xa and Xb are connected in series via aconnection 3200. The poly-phase winding 31 may have a star connection ora ring connection. These connections between the phase windings areformed outside the stator core 32.

As shown in FIGS. 4, 5 and 6, one of the sub-winding sets 31 a or 31 boccupies two radially adjacent pair of layers in the slot 35. The phasewinding Xa in the first sub-winding set occupies the outer-most layerand the outer-middle layer. The phase winding Xb in the secondsub-winding set occupies the inner-middle layer and the inner-mostlayer. The same applies to the other phases. The half portions 313 and314 on the same layer are inclined in the same direction and arecircumferentially spaced apart. Further, the half portions in the samelayer are inclined in the different direction to the half portions inthe adjacent layer. For instance, the half portions 313 in theouter-most layer cross the half portions 314 in the outer-middle layer.

In this embodiment, each of the sub-winding sets 31 a and 31 b areradially stacked in the slots 35. Therefore, the turn portions 312 c arearranged side by side with respect to a radial direction on both sidesof the stator core. The turn portions 312 c are regularly arranged toavoid collisions except for regions in which the irregular turn portions312 d are disposed. Almost all of the turn portions 312 c have gapsbetween them. The turn portions 312 d and the turn portions 312 ccrossing with the turn portion 312 d may have extra length and morecomplicated shape to avoid each other.

FIG. 7 shows a second embodiment of the present invention. Thepoly-phase winding has two sub-winding sets which are arrangedcircumferentially. Therefore, straight portions 100 and 101, straightportions 102 and 103, and turn portions 412 c are arrangedcircumferentially. As a result, a poly-phase winding which has fourturns (4T) in each phase is provided. The slot 351 has a narrower widththan that of the teeth 321 formed between slots 351 to provide widergaps between the turn portions 412 c.

In the first and second embodiment, more sub-winding sets may be used toprovide more wires in the slot to achieve a desired output. Forinstance, additional third and fourth sub-winding sets can be used. Thepoly-phase winding described in the second embodiment may be used as thesub-winding set in the first embodiment to provide an 8T winding.

FIGS. 8 through 12 show a third embodiment of the present invention.FIG. 8 shows a general structure of the alternator. FIG. 9 through FIG.12 show a manufacturing process of an individual phase winding.

The alternator 1 has a similar construction to the first embodimentexcept for a poly-phase winding 531. The poly-phase winding 531 hasportions 502 accommodated in the stator core 32, a first coil end group510 disposed on a rear side and a second coil end group 520 disposed ona front side. The first coil end group 510 has inner coil end 512 andouter coil ends 514 which are arranged side by side with respect to aradial direction. The inner and outer coil ends 512 and 514 are arrangedcircumferentially in a concentric arrangement. The second coil end group520 has large coil ends 522 and small coil ends 524 which are arrangedin a surrounding manner. The large coil ends 522 surround the small coilends 524. The coil ends are regularly arranged except for regions whereirregular coil ends are disposed. The coil ends are regularly arrangedto avoid collisions. Almost all of the coil ends have gaps between them.

In a manufacturing process, the poly-phase winding is individuallyformed and assembled with the stator core 32. The poly-phase winding isa three phase winding that has X, Y and Z windings. The followingprocess simultaneously forms these three windings.

FIG. 9 shows a phase winding X after a first step. FIG. 10 shows awiring diagram of the phase winding X. Two wave windings are formed in afirst step. The phase winding X is made of a continuous jointless wirefrom a start end 540 to a finish end 550. The phase winding X isarranged into a cylindrical shape.

The winding has straight portions 530 and turn portions 512 and 514 asthe inner and outer coil ends. The straight portions 530 have innerlayers 532 and outer layers 534. The turn portions. 512 and 514 haveregular turn portions 512 a and 514 a and an irregular turn portion 514b. The straight portions 530 and the turn portions 512 and 514 arealternately connected to form a wave winding from the start end 540 to athirty-fourth slot in order ascending. An irregular turn portion 514 bis used between the thirty-fourth and first slots to provide a reverseconnection. Then, a reverse wave winding is formed from the first slotto the finish end 550 through a fourth slot in order descending.

The turn portions 512 and 514 connect a pair of two straight portions530 which are spaced apart by a predetermined magnetic pole pitch. Theregular turn portions 512 a and 514 a are twisted to connect thestraight portions 530 in the different layers 532 and 534. The irregularturn portion 514 b is not twisted to connect the straight portions 530in the same layers 532.

FIG. 11 shows the phase winding X after a second step. In the secondstep, two straight portions 502 and shifting portions 505 are formed bytwisting the straight portions 530. The straight portions 502 are formedas portions accommodated in the slots. Each of the straight portions 502has a length corresponding to an axial length of the stator core 32. Theshifting portions 505 are formed as the second coil end group 520 in thecenter of the straight portions 530. The shifting portions 505 areshifted by a magnetic pole pitch. For instance, the sifting portions 505offset corresponding straight portions 502 by three slots. In FIGS. 10and 11, the solid line indicates outer layers and the broken lineindicates inner layers.

FIG. 12 shows the phase winding after a third step. The windings arefolded at the center of the shifting portions 505 to form the secondcoil end group 520. As a result, the phase winding X has four layeredstraight portions 502. In FIG. 12, the solid line indicates outer-mostlayers, the broken line indicates outer-middle layers, the chain lineindicates inner-most layers and the chain double-dashed line indicatesinner-middle layers.

The phase windings Y and Z are also formed with the phase winding X fromthe first step in a similar manner. Therefore, a cylindrically arrangedpoly-phase winding which has three phase windings is provided. Thepoly-phase winding is mounted on the stator core 32 and assembled into astar or ring connection in the same manner as described in the firstembodiment.

In this embodiment, almost all of the turn portions are regularlyarranged to prevent collisions. This avoids the need for an extrabending process, complex shaped turn portions or an extra length of theturn portion so as to prevent collisions. It is possible to reduce ajoining process between conductor segments and an additional insulatingprocess.

In the third embodiment, the ends 540 and 550 extend from the first coilend group 510. However, the ends 540 and 550 may extend from the secondcoil end group 520 by providing the ends 540 and 550 on the center ofthe straight portions 530.

FIG. 13 shows a fourth embodiment of the present invention. In thisembodiment, the winding is folded three times to provide six wires inthe slot. The stator 603 has a first coil end group 610 and a secondcoil end group 620. The first coil end group 610 has a surrounding coilend group 612 which has large coil ends 614 and small coil ends 616. Thefirst coil end group 610 also has inner coil ends 618. Therefore, thesurrounding coil end group 612 also provides outer coil ends paired withthe inner coil ends 618. Likewise, the second coil end group 620 has asurrounding coil end group 622 which has large coil ends 624 and smallcoil ends 626. The first coil end group 620 also has outer coil ends 628to be paired with the surrounding coil end group 622. Therefore, thewinding provides the concentric arrangement and the surroundingarrangement on both sides.

A flat or rectangular cross section wire may be used instead of a roundcross section wire. Each wire may be composed of a plurality of finewires to provide a flexible cross section. This wire can be insertedinto the slots without the deforming process even when the inner openingis narrower. Further, it is possible to help the plastic deformation ofthe ends 322 by heating the portion to be deformed by supplying currentin a concentrated manner.

The present invention may apply to a stator which has an even number ofaccommodated portions layered in one of the slot. The poly-phase windingmay have more than three phase windings. The number of slots 35 isvariable according to the number of magnetic poles and the number ofphases. The present invention may apply to a generator, a motor or arotary electric machine that selectively acts as a generator and amotor. The present invention may apply to a stator of an alternator forvehicle such as passenger vehicle, truck and shipping.

Although the present invention has been described in connection with thepreferred embodiments thereof with reference to the accompanyingdrawings, it is to be noted that various changes and modifications willbe apparent to those skilled in the art. Such changes and modificationsare to be understood as being included within the scope of the presentinvention as defined in the appended claims.

1. A method for manufacturing a stator of a rotary electric machinecomprising a stator core having a plurality of slots opening inside anda stator winding having a plurality of phase-windings, the methodcomprising: a step of forming from a continuous wire a plurality ofcircumferentially neighboring coils, each said coil having a pair ofgenerally straight portions which are one-magnetic-pole-pitchcircumferentially shifted from each other and first and second coil endportions at opposite axial ends; a step of bending each of said straightportions at the middle thereof to provide a pair of slot-accommodatedportions to be accommodated in a pair of the slots which areone-magnetic-pole-pitch shifted in a circumferential direction and ashifting portion between the slot-accommodated portions; and a step ofbending said shifting portion at the middle thereof so that the secondcoil end portion overlaps the first coil end portion of one of the coilsneighboring thereto and said shifting portion forms a third coil endportion located opposite said first and second coil end portions,thereby forming one of a plurality of phase windings.
 2. The methodaccording to claim 1, further comprising a step of mounting saidplurality of phase windings in the slots of the stator core, whereinsaid mounting step comprises a step of inserting the stator winding fromone end of the slots in an axial direction of the stator core and a stepof narrowing radially inner openings of the slots.
 3. The methodaccording to claim 1, wherein the plurality of circumferentiallyneighboring coils are wave wound coils.
 4. A method for manufacturing astator of a rotary electric machine comprising a stator core having aplurality of slots opening inside and a stator winding having aplurality of wave-wound phase-windings, the method including a step offorming a wave-wound phase-winding, wherein said step of forming thewave-wound phase-winding comprises a step of forming from a continuouswire a plurality of circumferentially neighboring wave-wound coils, eachsaid coil having a pair of generally straight portions which areone-magnetic-pole-pitch circumferentially shifted from each other andfirst and second coil end portions at opposite axial ends, a step ofbending each of said straight portions at the middle thereof to providea pair of slot-accommodated portions to be accommodated in a pair of theslots which are one-magnetic-pole-pitch shifted in a circumferentialdirection and a shifting portion between the slot-accommodated portions,and a step of bending said shifting portion at the middle thereof sothat the second coil end portion overlaps the first coil end portion ofone of the coils neighboring thereto and said shifting portions forms athird coil end portion located opposite said first and second coil endportions.